Dynamic Multi-Server Searchable Encryption Scheme Based on Concept Hierarchy

Due to the prevalent trend of cloud storage, data owners are motivated to outsource their private data to the cloud server. However, to ensure the security and privacy of their data, data owners might expect to store them in multiple cloud servers with the form of ciphertext. In previous studies, keywords are frequently used to retrieve the encrypted target data, which ignores the conceptual relationship between keywords and cannot return exact query results especially when users enter imprecise keywords. In this paper, it presents a Dynamic Multi-server Searchable Encryption Scheme Based on Concept Hierarchy to solve the problem. It designs the respective index of sub-servers and documents using the concept hierarchy tree, which can locate the most relevant cloud servers in order to improve the retrieval efficiency. And meanwhile it introduces TF*IDF method to further enhance the accuracy of retrieval. Simulation experiments demonstrate the advantages of our scheme when compared with other typical schemes.